Light emitting device and method for manufacturing the same

ABSTRACT

A light emitting device according to an embodiment includes a second electrode layer comprising at least one projection part; at least one current blocking layer on the projection part of the second electrode layer; a second conductive type semiconductor layer on the second electrode layer and the current blocking layer; an active layer on the second conductive type semiconductor layer; a first conductive type semiconductor layer on the active layer; and a first electrode layer on the first conductive type semiconductor layer, at least a portion of the first electrode layer corresponding with the current blocking layer in a vertical direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. 119 and 35U.S.C. 365 to Korean Patent Application No. 10-2008-0116751 filed onNov. 24, 2008, which is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

Embodiments relate to a light emitting device and a method formanufacturing the same.

Recently, an apparatus using a light emitting diode (LED) has beenwidely studied as a light emitting device.

The LED is an apparatus to convert electrical signals to light usingcharacteristics of a semiconductor, wherein a first conductive typesemiconductor layer, an active layer, and a second conductive typesemiconductor are stacked and then power is applied to the stackedstructure so that light is emitted from the active layer. The firstconductive type semiconductor layer may be an n-type semiconductor layerand the second conductive type semiconductor layer may be a p-typesemiconductor layer. Alternatively, the first conductive typesemiconductor layer may be a p-type semiconductor layer and the secondconductive type semiconductor layer may be an n-type semiconductorlayer.

Meanwhile, in a vertical LED structure where a first electrode layerapplying power to the first conductive type semiconductor and a secondelectrode layer applying power to the second conductive typesemiconductor layer are overlapped in a vertical direction, a phenomenonwhere the electric current is concentrated on the bottom or lower sideof the first electrode layer may occur.

When this phenomenon occurs, the operating voltage of the light emittingdevice is raised, the life span of the light emitting device isdecreased, and reliability of the light emitting device is deteriorated.

Also, as the light is generated mainly from the active layer on thelower side of the first electrode layer, the generated light is notcompletely output to the external of the light emitting device but isreflected on the first electrode layer to be absorbed by the lightemitting device, thereby deteriorating the optical efficiency of thelight emitting device.

SUMMARY OF THE INVENTION

Embodiments provide a light emitting device having a new structure and amethod for manufacturing the same.

Embodiments provide a light emitting device that can remove or reduce acurrent concentration phenomenon and a method for manufacturing thesame.

Embodiments provide a light emitting device that can be driven at astable operation voltage and be stably operated without thedeterioration in the light intensity and a method for manufacturing thesame.

Embodiments also provide a light emitting device and a method forforming the same, which address the limitations and disadvantagesassociated with the related art.

In an embodiment, a semiconductor light emitting device comprises: asecond electrode layer comprising a projection part; a current blockinglayer on the projection part of the second electrode layer; a secondconductive type semiconductor layer on the second electrode layer andthe current blocking layer; an active layer on the second conductivetype semiconductor layer; a first conductive type semiconductor layer onthe active layer; and a first electrode layer on the first conductivetype semiconductor layer, at least a portion of the first electrodelayer being overlapped with the current blocking layer in the verticaldirection.

In an embodiment, a light emitting device comprises: a second electrodelayer; current blocking layers on the central portion and the peripheralportion of the second electrode layer; a second conductive typesemiconductor layer on the second electrode layer and the currentblocking layers; an active layer on the second conductive typesemiconductor layer; a first conductive type semiconductor layer on theactive layer; and a first electrode layer on the first conductive typesemiconductor layer, at least a portion of the first electrode layerbeing overlapped with the current blocking layers in the verticaldirection.

In an embodiment, a light emitting device comprises: a second electrodelayer; a current blocking layer on the second electrode layer; a secondconductive type semiconductor layer on the second electrode layer andthe current blocking layer; an active layer on the second conductivetype semiconductor layer; a first conductive type semiconductor layer onthe active layer; and a first electrode layer on the first conductivetype semiconductor layer, at least a portion of the first electrodelayer being overlapped with the current blocking layer in the verticaldirection.

In an embodiment, the preset invention provides a light emitting device,comprising: a second electrode layer comprising at least one projectionpart; at least one current blocking layer on the projection part of thesecond electrode layer; a second conductive type semiconductor layer onthe second electrode layer and the current blocking layer; an activelayer on the second conductive type semiconductor layer; a firstconductive type semiconductor layer on the active layer; and a firstelectrode layer on the first conductive type semiconductor layer, atleast a portion of the first electrode layer corresponding with thecurrent blocking layer in a vertical direction.

In an embodiment, the present invention provides a light emittingdevice, comprising: a second electrode layer; current blocking layers ona central portion and at least one peripheral portion of the secondelectrode layer; a second conductive type semiconductor layer on thesecond electrode layer and the current blocking layers; an active layeron the second conductive type semiconductor layer; a first conductivetype semiconductor layer on the active layer; and a first electrodelayer on the first conductive type semiconductor layer and correspondingwith at least one of the blocking layers.

In an embodiment, the present invention provides a light emittingdevice, comprising: a second electrode layer; a first current blockinglayer on the second electrode layer; a second conductive typesemiconductor layer on the second electrode layer and the first currentblocking layer; an active layer on the second conductive typesemiconductor layer; a first conductive type semiconductor layer on theactive layer; and a first electrode layer on the first conductive typesemiconductor layer, and being above the first current blocking layer ina vertical direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 5 are diagrams illustrating and explaining a light emittingdevice according to a first embodiment of the invention, and a methodfor manufacturing the same.

FIG. 6A is a diagram illustrating and explaining a light emitting deviceaccording to a second embodiment of the invention, and

FIG. 6B is a diagram illustrating a variation of the light emittingdevice of FIG. 6B.

FIG. 7 is a diagram illustrating and explaining a light emitting deviceaccording to a third embodiment of the invention.

FIG. 8A is a diagram illustrating and explaining a light emitting deviceaccording to a fourth embodiment of the invention, and FIG. 8B is a topplan view of the light emitting device of FIG. 8A cut along a dottedline 8B-8B in FIG. 8A.

FIG. 9 is a diagram illustrating and explaining light extractioncharacteristics of a light emitting device according to embodiments ofthe invention.

FIGS. 10 and 11 are diagrams showing experimental structures forexplaining ohmic contact characteristics and schottky contactcharacteristics by forming a metal that forms an ohmic contact and ametal that forms a schottky contact on a second conductive typesemiconductor layer, and experimental results thereof, according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the description of embodiments of the invention, when a layer (e.g.,film), area, pattern or structure(s) are described to be formed “on”,“over”, or “under” another layer (e.g., film), area, pattern orstructure(s), it can be understood that the layer, area, pattern orstructures are in direct contact with the another layer, area, patternor structures or that other layer(s) (e.g., films), area(s), pattern(s)or structure(s) are additionally formed therebetween.

In the drawings, the thickness or size of each layer may have beenexaggerated, omitted or schematically illustrated for the convenienceand clarity of explanation. Also, the size of each constituent does notor may not necessarily reflect its actual size.

Hereinafter, a light emitting device according to embodiments of theinvention and a method for manufacturing the same according to theembodiment of the invention will be described in detail with referenceto the accompanying drawings.

FIGS. 1 to 5 are diagrams explaining a light emitting device accordingto a first embodiment, and a method for manufacturing the same.

First, referring to FIG. 5, the light emitting device according to thefirst embodiment includes a second electrode layer 90, one or morecurrent blocking layers 70 selectively formed on the second electrodelayer 90, a second conductive type semiconductor layer 50 on the secondelectrode layer 90 and the current blocking layer(S) 70, an active layer40 and a first conductive type semiconductor layer 30 formed on theactive layer 40, and a first electrode layer 100 formed on the firstconductive type semiconductor layer 30. All the components of the lightemitting device are operatively coupled and configured.

The current blocking layer(s) 70 are formed between the second electrodelayer 90 and the second conductive type semiconductor layer 50, therebychanging the path of current flowing in the light emitting device.

Each current blocking layer 70 includes a metal that forms a schottkycontact with the second conductive type semiconductor layer 50. Forexample, each current blocking layer 70 may be formed of at least one oftitanium (Ti), zirconium (Zr), chrome (Cr), gold (Au) or tungsten (W),or an alloy including at least one of titanium (Ti), zirconium (Zr),chrome (Cr), gold (Au) or tungsten (W).

At least one current blocking layer 70 may be disposed to be overlappedwith the first electrode layer 100 in the vertical direction. Forexample, the first electrode layer 100 may be formed on a centralportion of the first conductive type semiconductor layer 30, and thecurrent blocking layer 70 may be formed under the first electrode layer100 to correspond with the location of the first electrode layer 100,e.g., on the central portion of the second electrode layer 90. Forinstance, the current blocking layer 70 may align completely orsubstantially with the first electrode layer 100.

In addition to or in lieu of the current block layer formed tocorrespond with the first conductive type semiconductor layer 30, one ormore current blocking layers 70 may also be formed on peripheralportion(s) of the second electrode layer 90. For instance, the currentblocking layers 70 may be formed at regular intervals or non-regularintervals or as needed on the second electrode layer 90.

Meanwhile, in an area where the current blocking layer 70 is not formed,the second electrode layer 90 forms an ohmic contact with the secondconductive type semiconductor layer 50.

Therefore, as shown in FIG. 5 using the dotted lines, the currentflowing from the second electrode layer 90 to the first electrode layer100 hardly flows through the area(s) having the current blockinglayer(s) 70 formed therein, but flows from the second electrode layer 90to the first electrode layer 100 in the area(S) where the currentblocking layer(s) 70 are not formed. As such, the electric current flowis not concentrated on a narrow path, but is spread out in a wider path,which reduces or eliminates the current concentration phenomenon.

The second electrode layer 90 may include a conductive substrate, areflective layer formed on the conductive substrate, and an ohmiccontact layer formed on the reflective layer. Also, the second electrodelayer 90 may be formed of a material that forms an ohmic contact withthe second conductive type semiconductor layer 50.

For example, the conductive substrate in the second electrode layer 90may be formed of at least one of copper (Cu), titanium (Ti), chrome(Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), asemiconductor substrate implanted with impurity; the reflective layermay be formed of at least one of aluminum (Al), silver (Ag), and APCalloy (alloy including Ag, Pd, and Cu); and the ohmic contact layer maybe formed of at least one of nickel (Ni), palladium (Pd), platinum (Pt),ITO, ZnO, RuO_(x), TiO_(x) and IrO_(x).

The second electrode layer 90 may contact (touch directly) the lowersurface and the side surface of the current blocking layer(s) 70. Theupper surface of the second electrode layer 90 may be positioned on thesame horizontal plane with the upper surface of the current blockinglayer(s) 70.

FIGS. 10 and 11 are diagrams showing experimental structures forexplaining ohmic contact characteristics and schottky contactcharacteristics by forming a metal that forms an ohmic contact and ametal that forms a schottky contact on a second conductive typesemiconductor layer, and experimental results thereof, according to anembodiment of the invention. These are non-limiting examples forexplaining the invention and the advantages associated thereto.

Referring to FIGS. 10 and 11, a plurality of ohmic metal layers 91 (oneexample of a current blocking layer) and a plurality of schottky metallayers 71 (another example of a current blocking layer) are formed on ap-type GaN layer 51 (example of second conductive type semiconductorlayer 50), respectively, where the plurality of ohmic metal layers 91and the plurality of schottky metal layers 71 are spaced apart from eachother.

First, if a positive voltage and a negative voltage are applied to twoohmic metal layers 91 of the plurality of ohmic metal layers 91,respectively, current flows from one ohmic metal layer 91 to the otherohmic metal layer 91 via the p-type GaN layer 51 in the horizontaldirection.

In one experiment, the interval or space ‘d’ between the two ohmic metallayers 91 is adjusted to be 20 μm, 30 μm, 40 μm, 60 μm, and 80 μm. Theresult of this experiment shows the ohmic barrier characteristics, asshown in FIG. 10.

Next, if a positive voltage and a negative voltage are applied to twoschottky metal layers 71 of the plurality of schottky metal layers 71,respectively, current flows from one schottky metal layer 71 to theother schottky metal layer 71 via the p-type GaN layer 51 in thehorizontal direction.

In this experiment, the interval ‘d’ between the two schottky metallayers 71 is adjusted to be 20 μm, 30 μm, 40 μm, 60 μm, and 80 μm. Theresult of this experiment shows schottky barrier characteristics, asshown in FIG. 11.

As evidenced by the above experiments, it can be appreciated that withthe light emitting device according to the first embodiment, the ohmicbarrier characteristics and the schottky barrier characteristics areshown and vary according to the kind of metal (current blocking layer)contacting the second conductive type semiconductor layer 50.

Therefore, with the light emitting device according to the firstembodiment, the current blocking layer 70 having the schottky barriercharacteristics is formed on a position overlapped with (orsubstantially aligned with) the first electrode layer 100 in thevertical direction, thereby preventing the current from concentratedlyflowing in the vertical direction from only a certain portion of thesecond electrode layer 90 to the lower side of the first electrode layer100 and thereby allowing the current to more widely flow to the secondconductive type semiconductor layer 50, the active layer 40 and thefirst conductive type semiconductor layer 30.

Finally, the current concentration phenomenon where the current flowsconcentratedly to the lower side of the first electrode layer 100 can beprevented so that the light emitting device can be driven at stableoperation voltages.

Also, according to the current concentration phenomenon, when thecurrent flows concentratedly to the lower side of the first electrodelayer 100, light is mainly generated from the area of the active layer40 positioned under the lower side of the first electrode layer 100. Thelight generated from the active layer 40 under the first electrode layer100 is absorbed by the first electrode layer 100 so that the quantity oflight is highly likely to be decreased or to be disappeared in the lightemitting device.

In contrast, in the light emitting device according to the firstembodiment of the invention, current flows from the second electrodelayer 90 in the area not overlapped with the first electrode 100 in thevertical direction to the first electrode layer 100, so that more lightis generated from the area(s) of the active layer 40 not overlapped withthe first electrode layer 100 in the vertical direction, compared to thearea of the active layer 40 overlapped with the first electrode layer100 in the vertical direction.

And, the light generated from the area(s) of the active layer 40 notoverlapped with the first electrode layer 100 in the vertical directionare hardly absorbed by the first electrode layer 100 so that thequantity of light is not likely to be decreased or to be disappeared inthe light emitting device. Therefore, the light emitting deviceaccording to the embodiment has improve optical efficiency and iseffective.

Meanwhile, in the light emitting device according to the firstembodiment, the current blocking layers 70 are formed on the peripheralportions of the second electrode layer 90. As a result, current flowingto the peripheral portions adjacent to the side surface of the lightemitting device can be reduced and accordingly, the leakage current ofthe light emitting device can be also reduced.

Hereinafter, a method for manufacturing the light emitting deviceaccording to the first embodiment will be described in detail withreference to the accompanying drawings.

FIGS. 1 to 5 are diagrams explaining a light emitting device accordingto the first embodiment, and a method for manufacturing the same.

Referring to FIG. 1, a un-doped GaN layer 20, a first conductive typesemiconductor layer 30, an active layer 40, and a second conductive typesemiconductor layer 50 are formed on a substrate 10. Also, a bufferlayer (not shown) may further be formed between the substrate 10 and theun-doped GaN layer 20.

The substrate 10 may be formed of at least one of sapphire (Al₂O₃), Si,SiC, GaAs, ZnO, and MgO.

The buffer layer may be formed in a multi layer having a stackedstructure such as AlInN/GaN, In_(x)Ga_(1-x)N/GaN,Al_(x)In_(y)Ga_(1-w-y)N/In_(x)Ga_(1-x)N/GaN, etc., and for example, itmay grow by implanting trimethylgallium (TMGa), trimethylindium (TMIn),and trimethylaluminum (TMAl) into the chamber, together with hydrogengas and ammonium gas.

The un-doped GaN layer 20 may grow by implanting trimethylgallium (TMGa)into the chamber, together with hydrogen gas and ammonium gas.

The first conductive type semiconductor layer 30 may be a nitridesemiconductor layer implanted with first conductive type impurity ions,for example, a semiconductor layer implanted with n-type impurity ions.The first conductive semiconductor layer 30 may grow by implantingtrimethylgallium (TMGa) and siren gas (SiN₄) including n-type impurity(for example, Si) into the chamber, together with hydrogen gas andammonium gas.

And, the active layer 40 and second conductive type semiconductor layer50 are formed on the first conductive type semiconductor layer 30.

The active layer 40 may be formed in a single-quantum well structure orin a multi-quantum well structure, for example, in a stacked structureof InGaN well layer/GaN barrier layer.

The second conductive type semiconductor layer 50 may be a nitridesemiconductor layer implanted with second conductive type impurity ions,for example, a semiconductor layer implanted with p-type impurity ions.The second conductive type semiconductor layer 50 may grow by implantingtrimethylgallium (TMGa) and bisethylcyclopentadienyl magnesium (EtCp₂Mg){Mg(C₂H₅C₅H₄)₂} into the chamber, together with hydrogen gas andammonium gas.

And, mask layers 60 are formed on the second conductive typesemiconductor layer 50. The mask layers 60 are used for selectivelyforming the current blocking layers 70 on the second conductive typesemiconductor layer 50.

Referring to FIG. 2, if a metal that forms a schottky contact isdeposited on the second conductive type semiconductor layer 50 on whichthe mask layers 60 are formed and then the mask layers 60 are removed,current blocking layers 70 are selectively formed on the secondconductive type semiconductor layer 50.

For example, the metal that forms a schottky contact may use at leastone of titanium (Ti), zirconium (Zr), chrome (Cr), gold (Au) or tungsten(W).

Referring to FIG. 3, after forming the current blocking layers 70, thesecond electrode layer 90 is formed on the second conductive typesemiconductor layer 50 and the current blocking layers 70.

The second electrode layer 90 may include an ohmic contact layer, areflective layer, and a conductive substrate. The ohmic contact layermay be formed on the second conductive type semiconductor layer 50 andthe current blocking layers 70, and the reflective electrode layer andthe conductive substrate may be formed on the ohmic contact layer.Alternatively, the conductive substrate or the reflective layer havingthe ohmic contact characteristics may be formed directly on the secondconductive type semiconductor layer 50.

Referring to FIG. 4, after forming the second electrode layer 90, thesubstrate 10 and the un-doped GaN layer 20 are removed. When a bufferlayer is formed, the buffer layer is also removed.

Referring to FIG. 5, the first electrode layer 100 is formed on thefirst conductive type semiconductor layer 30.

The first electrode layer 100 may be formed of at least one of copper(Cu), titanium (Ti), chrome (Cr), nickel (Ni), aluminum (Al), platinum(Pt), or gold (Au).

Accordingly, through the methods as described above, the light emittingdevice according to the first embodiment can be manufactured.

FIG. 6A is a diagram explaining a light emitting device according to asecond embodiment.

When explaining the light emitting device according to the secondembodiment, the description overlapped with the light emitting deviceaccording to the first embodiment will be omitted.

Referring to FIG. 6A, the light emitting device according to the secondembodiment includes a second electrode layer 90 that includes aprojection part 91, a current blocking layer 70 formed on the projectionpart 91, a second conductive type semiconductor layer 50 formed on thesecond electrode layer 90 and the current blocking layer 70, an activelayer 40 formed on the second conductive type semiconductor layer 50, afirst conductive type semiconductor layer 30 formed on the active layer40, and a first electrode layer 100 formed on the first conductive typesemiconductor layer 30.

The current blocking layer 70 is formed between the second electrodelayer 90 and the second conductive semiconductor layer 50, therebychanging the path of current flowing in the light emitting device.

The current blocking layer 70 includes a metal that forms a schottkycontact with the second conductive type semiconductor layer 50. Forexample, the current blocking layer 70 may be formed of at least one oftitanium (Ti), zirconium (Zr), chrome (Cr), gold (Au) or tungsten (W),or an alloy including at least one of titanium (Ti), zirconium (Zr),chrome (Cr), gold (Au) or tungsten (W).

At least a portion of the projection part 91 may be disposed to beoverlapped with (or correspond with) the first electrode layer 100 inthe vertical direction, and accordingly, at least a portion of thecurrent blocking layer 70 may be disposed on the projection part 91 tooverlap with or correspond with the first electrode layer 100 in thevertical direction. For example, the first electrode layer 100 may beformed on a central portion of the first conductive type semiconductorlayer 30, and the current blocking layer 70 may be formed under thefirst electrode layer 100, e.g., on the central portion of the secondelectrode layer 90.

At least a portion of the current blocking layer 70 is disposed on thesame horizontal plane with the second conductive type semiconductorlayer 50, and at least a portion of the second electrode layer 90 isdisposed on the same horizontal plane with the second conductive typesemiconductor layer 50. Also, at least portions of the current blockinglayer 70, the second electrode layer 90, and the second conductive typesemiconductor layer 50 may be disposed on the same horizontal plane.

In the light emitting device according to the second embodiment, thecurrent blocking layer 70 serves to change the flow of current as in thelight emitting device according to the first embodiment.

Also, since the current blocking layer 70 is formed on the projectionpart 91, the light emitted from the active layer is scattered by thecurrent blocking layer 70, making it possible to improve the lightextraction efficiency of the light emitting device.

In the light emitting device according to the second embodiment, thecurrent blocking layer 70 may be formed by forming a groove (orindentation) by selectively etching the second conductive typesemiconductor layer 50 and then burying a material having schottkycontact characteristics with the second conductive type semiconductorlayer 50 in the groove. And then, a second electrode layer 90 is formedon the current blocking layer 70 and the second conductive typesemiconductor layer 50, thereby making it possible to form the lightemitting device having the structure as shown in FIG. 6. The shape andsize of the projection part 91 and the current blocking layer 70 mayvary and the present invention encompasses such variations. Forinstance, the current blocking layer 70 may be in the shape of a “U” or“V” or a mere indentation.

FIG. 6B illustrates a variation of the light emitting device of FIG. 6Aaccording to the second embodiment. As shown in FIG. 6B, instead ofbeing formed on the projection part 91, the current blocking layer 70 ofFIG. 6B is formed directly on the flat part or coplanar surface of thesecond electrode 90, and can have a substantially triangular shape. Forinstance, the current blocking layer 70 of FIG. 6B can have atriangular/pyramid shape or an upside-down triangular/pyramid shape orsome other shape.

FIG. 7 is a diagram explaining a light emitting device according to athird embodiment.

When explaining the light emitting device according to the thirdembodiment, the description overlapped with the light emitting deviceaccording to the first embodiment and the second embodiment will beomitted.

Referring to FIG. 7, the light emitting device according to the thirdembodiment has current blocking layers that are a combination of thecurrent blocking layers of the first and second embodiments.

The current blocking layers 70 are formed on a central portion andperipheral portion(s) of the second electrode layer 90. Similarly, aprojection part 91 is formed on the central portion of the secondelectrode layer 90 to be overlapped with (or correspond with) the firstelectrode layer 100 in the vertical direction, and the current blockinglayer 70 is formed on the projection part 91.

The current blocking layer 70 formed on the central portion of thesecond electrode layer 90 is formed in the similar shape as the currentblocking layer 70 of the light emitting device according to the secondembodiment, and the current blocking layer(s) 70 formed on theperipheral portion(s) of the second electrode layer 90 are formed in thesimilar shape as the current blocking layers 70 according to the firstembodiment.

FIG. 8A is a diagram explaining a light emitting device according to afourth embodiment, and FIG. 8B is a top plan view of the light emittingdevice of FIG. 8A cut along a dotted line 8B-8B in FIG. 8A as avariation.

When explaining the light emitting device according to the fourthembodiment, the description overlapped with the light emitting deviceaccording to the first embodiment to the third embodiment will beomitted.

Referring to FIG. 8A, the light emitting device according to the fourthembodiment has the shape similar with the light emitting deviceaccording to the second embodiment.

The current blocking layers 70 are formed on a central portion andperipheral portion(s) of the second electrode 90. A projection part 91is formed on the central portion of the second electrode layer 90 to beoverlapped with or correspond with the first electrode layer 100 in thevertical direction, and the current blocking layer 70 is formed on theprojection part 91.

Also, additional projection part(s) 91 are formed on the peripheralportion(s) on the second electrode layer 90, and additional currentblocking layer(s) 70 are formed on the projection part(s) 91 tocorrespond with the additional projection part(s) 91. As such, a windowpattern or the like as shown in the top plan view of the currentblocking layer(s) 70 in FIG. 8B may be formed by the current blockinglayer(s) 70. As further variations, the current blocking layer(s) 70 maybe formed to surround only a part of the periphery of the secondelectrode 90, and thus may not completely surround it. All the currentblocking layers 70 can have the same or similar shape and/or size toeach other, or may have varying shapes and/or sizes.

In all the embodiments of the invention, the current blocking layer canbe formed with a non-metal or non-conductive material, e.g., SiO₂ orsimilar compound or material, other insulating material, ITO, ZnO, orIrO, etc.

FIG. 9 is a diagram explaining light extraction characteristics of alight emitting device according to embodiments.

Referring to FIG. 9, X axis represents distance from a left-sided end ofthe light emitting device to a right-sided end thereof in thecross-sectional view of FIG. 5, wherein the current blocking layers 70are disposed on portions corresponding to 0 to 50 μm, 225 to 275 μm, and450 to 550 μm. Y axis represents values that relatively represent thequantity of light extracted from the light emitting device on theassumption that the quantity of light generated from the light emittingdevice is 1.

In FIG. 9, the structure of the light emitting device in the related artmeans a structure where the current blocking layers 70 does not existand are not formed between the second conductive type semiconductorlayer 50 and the second electrode layer 90. In the structure of therelated art, more current flows towards the central portion so that thegreatest quantity of light is generated and extracted from the area ofthe active layer 40 overlapped with the first electrode layer 100 in thevertical direction.

In contrast, in the structure of the present invention, current flowsmainly through between the current blocking layer and the currentblocking layer 70 so that the greatest quantity of light is generatedand extracted from the active layer 40 on the position corresponding tothe area(s) where the current blocking layers 70 are not formed.

In the related art, the light generated from the area of the activelayer 40 overlapped with the first electrode layer 100 in the verticaldirection is absorbed by the first electrode layer 100 so that thequantity of light is highly likely to be decreased or to be disappearedin the light emitting device.

Meanwhile, in the present embodiment, as shown in FIG. 9, since a greatquantity of light is generated from the area of the active layer 40 notoverlapped with the first electrode layer 100 in the vertical direction,the light is reflected on the first electrode layer 100, making itpossible to prevent or reduce the light disappearing in the lightemitting device.

Any reference in this specification to “one embodiment,” an embodiment,example embodiment, etc., means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. The appearances of suchphrases in various places in the specification are not necessarily allreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anyembodiment, it is submitted that it is within the purview of one skilledin the art to effect such feature, structure, or characteristic inconnection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A light emitting device, comprising: a second electrode layercomprising at least one projection part; a current blocking layer on theprojection part of the second electrode layer; a second conductive typesemiconductor layer on the second electrode layer and the currentblocking layer; an active layer on the second conductive typesemiconductor layer; a first conductive type semiconductor layer on theactive layer; and a first electrode layer on the first conductive typesemiconductor layer, at least a portion of the first electrode layercorresponding with the current blocking layer in a vertical direction.2. The light emitting device according to claim 1, wherein the currentblocking layer extends along a central portion of the second electrodelayer and/or surrounds at least a portion of a periphery of the secondelectrode layer.
 3. The light emitting device according to claim 1,wherein the projection part is disposed at a central portion of thesecond electrode layer and/or a peripheral portion of the secondelectrode layer.
 4. The light emitting device according to claim 1,wherein the current blocking layer is formed of at least one of titanium(Ti), zirconium (Zr), chrome (Cr), gold (Au) or tungsten (W), or analloy comprising at least one of titanium (Ti), zirconium (Zr), chrome(Cr), gold (Au) or tungsten (W).
 5. The light emitting device accordingto claim 1, wherein the current blocking layer includes a first currentblocking layer disposed on the projection part of the second electrodelayer, and a second current blocking layer disposed at an indented areaof the second electrode layer.
 6. The light emitting device according toclaim 5, wherein the first current blocking layer is disposed at acentral portion of the second electrode layer, and the second currentblocking layer is disposed at a peripheral portion of the secondelectrode layer.
 7. The light emitting device according to claim 1,wherein the projection part includes a plurality of projection parts,and the current blocking layer includes a plurality of current blockinglayers spaced apart from each other and disposed respectively on theplurality of projection parts.
 8. The light emitting device according toclaim 7, wherein the plurality of current block layers are disposed at acentral portion of the second electrode layer and at least oneperipheral portion of the second electrode layer.
 9. The light emittingdevice according to claim 1, wherein the current blocking layer forms aschottky contact with the second conductive type semiconductor layer,and the second electrode layer forms an ohmic contact with the secondconductive type semiconductor layer.
 10. The light emitting deviceaccording to claim 1, wherein the current blocking layer is disposed ona curved surface or slanted surfaces of the projection part.
 11. A lightemitting device, comprising: a second electrode layer; a currentblocking layer the second electrode layer; a second conductive typesemiconductor layer on the second electrode layer and the currentblocking layer; an active layer on the second conductive typesemiconductor layer; a first conductive type semiconductor layer on theactive layer; and a first electrode layer on the first conductive typesemiconductor layer, wherein the current blocking layer is disposed onthe second electrode layer and has a substantially triangular shape. 12.The light emitting device according to claim 11, wherein the currentblocking layer is disposed on a central portion of the second electrodelayer and at least one peripheral portion of the second electrode layer.13. The light emitting device according to claim 11, wherein the currentblock layer is overlapped with the first electrode layer in a verticaldirection.
 14. The light emitting device according to claim 11, whereinthe current blocking layer forms a schottky contact with the secondconductive type semiconductor layer and the second electrode layer formsan ohmic contact with the second conductive type semiconductor layer.15. A light emitting device, comprising: a second electrode layercomprising a projection part; a first current blocking layer on thesecond electrode layer; a second conductive type semiconductor layer onthe second electrode layer and the first current blocking layer; anactive layer on the second conductive type semiconductor layer; a firstconductive type semiconductor layer on the active layer; and a firstelectrode layer on the first conductive type semiconductor layer,wherein the first current blocking layer is disposed on the projectionpart of the second electrode layer.
 16. The light emitting deviceaccording to claim 15, wherein the first current blocking layer isdisposed directly on the second electrode layer and has a shapesubstantially corresponding with the projection part.
 17. The lightemitting device according to claim 15, wherein the first currentblocking layer is aligned with the first electrode layer.
 18. The lightemitting device according to claim 15, wherein the first currentblocking layer is overlapped with the first electrode layer in avertical direction and the first conductive semiconductor layer includesan n-type impurity.
 19. The light emitting device according to claim 18,further comprising: a second current blocking layer spaced apart fromthe first current blocking layer, and formed on another projected partof the second electrode layer or in an indented area of the secondelectrode layer.
 20. The light emitting device according to claim 19,wherein at least one of the first and second current blocking layersforms a schottky contact with the second conductive type semiconductorlayer.
 21. The light emitting device according to claim 20, wherein atleast one of the first and second current blocking layers is formed ofat least one of titanium (Ti), zirconium (Zr), chrome (Cr), gold (Au) ortungsten (W), or an alloy comprising at least one of titanium (Ti),zirconium (Zr), chrome (Cr), gold (Au) or tungsten (W).